Integrated circuit devices with multiple stacked integrated circuits often include an interposer as a medium to couple the different integrated circuits together. The interposer is generally placed between the integrated circuits and a package substrate. The interposer may have signal pathways that can be used for transmitting data between two or more integrated circuits mounted on the interposer, or between one of the integrated circuits on the interposer and components mounted directly on the package substrate.
Interposers are typically formed from silicon substrates. However, interposers formed from silicon wafers may be brittle. Hence, complex manufacturing processes may be required to produce such interposers. Active and passive devices may be embedded in the silicon interposers. However, they usually have poor signal transmission characteristics (e.g., poor insertion loss and poor return loss). Therefore, silicon interposers may be unsuitable for high frequency applications.
Another type of wafer that may be used to form interposers is a glass wafer (or a non-semiconductor wafer). A glass interposer does not include any silicon substrate material and may exhibit better signal transmission characteristics compared to a silicon interposer. However, active circuits (i.e., transistor) cannot be embedded in a glass interposer.